<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
	</head>
	<body>
		<script>
			var num1=prompt("请输入第一个数:")*1;
			var caclu=prompt("请输入运算符:");
			var num2=prompt("请输入第二个数:")*1;
			switch(caclu)
			{
				case '*':document.write(num1*num2);
				break;
				case '/':document.write(num1/num2);
				break;
				case '+':document.write(num1+num2);
				break;
				case '-':document.write(num1-num2);
				break;
			}
		</script>
	</body>
</html>
